In Blender, is it possible to assign lighting objects/effects exclusively to a single mesh? For instance, if I place two meshes next to each other, and two lights (one shining on each mesh), I would want each mesh to not cast a cast any shadow on the other.
For example, in the following rendered image from a "test" star system view:

The rings are casting shadows on the right-most planets. I want the rings to only cast shadows on their own planet.
Is this possible?